Ask the average parent that question, and he or she will likely experience a moment of confusion before suggesting a vague list of contents: phone numbers, text messages, pictures of friends and maybe a couple of games.

What parents may not know is that the mobile devices carried by an estimated 78 percent of today’s teens often contain far more unsavory material. With school starting in a few weeks, and the majority of local youths soon toting a phone in their backpacks, the Los Gatos-Monte Sereno Police Department hopes to help parents ensure safe cell phone usage by the under-18 set.

Two years ago, juvenile detective Jamie Field took the initiative to undergo intensive training on new trends in mobile phone and Internet access by teens. In the past several years, the two have become inextricably linked: A March 2013 Pew Research Center study titled “Technology and Teens” reports that of the 78 percent of U.S. teens who now have cell phones, roughly “three in four (74 percent) of teens ages 12-17 are ‘mobile Internet users’ who say they access the Internet on cell phones, tablets and other mobile devices.” The study also finds that “95 percent of teens are online,” with Internet access transitioning “from stationary connections tied to desktops in the home to always-on connections that move with them throughout the day.”

This always-on model does have benefits, Field says, citing the use of social media by law enforcement agencies earlier this year to alert Boston residents to shelter in place prior to the capture of the alleged marathon bomber.

“That was brilliant,” Field says. “Boston’s a huge city; how else can you get information out quickly to that many people to make sure they’re safe? Using Twitter was extremely positive and efficient.”

But it is the darker side of social media–and its potential to have lasting, deleterious effects on youths–that concerns Field. Still mindful of the suicide of Saratoga High School student Audrey Pott, who took her life after compromising cell phone photos were taken of her at a party last year, Field and her colleagues aim to alert parents of the hazards of unfettered access to the Internet, primarily enabled via the ubiquitous phones.

“We’re seeing that we have to do something,” Field says. “There’s been a definite increase in kids sexting and sending inappropriate photos of themselves to each other and posting them on social media sites, cyberbullying, and a lot of other activities that are potentially really harmful. Parents need to be aware that ‘stranger danger’ is online, as well as on the sidewalk.”

Field encourages moms and dads to monitor their kids’ Internet access closely–even if it means taking a stance that’s sure to be wildly unpopular with their offspring. In virtually all cases where the child is under 18, she notes, the parent has purchased the cell phone and pays for all of the monthly charges, making the phone their property.

“That gives that parent the right to have their child’s password, and know exactly how the phone’s being used. And if that child is unwilling to provide the password, the answer’s simple: ‘I bought it, I can take it away from you,’ ” Field says.

Why go to the trouble of examining a teen’s phone? And isn’t that an invasion of privacy?

In Field’s view, it’s all about keeping kids safe. She says there are several sectors of the digital domain that present potential minefields, including social media sites that encourage contact with strangers, texting and sexting (sending harassing, provocative or explicit messages and photos via text), the use of web-cams to capture and exchange inappropriate videos and photos, and so-called “confession” sites and blogs that encourage users to reveal their most personal thoughts and feelings.

Field lists Omegle and Chatroulette as two sites that should be on parents’ radar-screens.

“Omegle’s motto is ‘talk to strangers,’ and they say it’s a ‘great way to meet new friends,'” she notes. “What happens when the new ‘friend’ your child is talking to online isn’t really another teen, but is actually some creepy older guy who’s victimized multiple other kids? When that individual gains your child’s trust, it becomes really easy to get the child to reveal where they live, where they go to school, even their credit card information.” The next step is arranging to meet in person.

“Parents need to know how and why and when their kids are accessing the Internet, and talk to them about people who are using it for the wrong reasons,” Field continues. “And here’s something teens never think of: If that new online friend isn’t actually a predator, it could well be an undercover officer who’s doing an investigation. Your child would probably be horrified to realize he or she has just ‘friended’ a cop, and shared a lot of intimate information.”

Field ticked off several recent cases of social media-driven tragedies, including that of Canadian teen Amanda Todd, who also committed suicide last year after a man she’d met on a “stranger” site convinced her to pose topless, later using the photos to stalk and harass her. Closer to home, Field just helped retrieve a local minor who had fled to another state to meet a man she’d met online.

“Thanks to YouTube she’d learned how to modify her birth certificate so she could buy a plane ticket. Fortunately, we were able to find her at the airport and bring her back here before she and the guy actually got together,” Field says.

Though the notion of parental cell phone control is practically guaranteed to spark backlash among teens, Field believes that families can and should work together to develop acceptable, safe usage policies. She recommends that such usage be captured in a written contract, with agreed upon consequences for misuse spelled out. She also advises that even though parents may not be tech-savvy, they should familiarize themselves with every feature of the phones they hand over to their kids.

“Juveniles often know how to override these features, so the best thing parents can do is talk to their cell phone provider and learn how to make sure those controls are in place,” Field says.

In all cases, she adds, parents must keep the dialogue flowing, even when it veers into unfamiliar (and uncomfortable) territory.

“You have to be involved in what your kids are doing, and sometimes that’s not about being their best friend,” she says. “It’s much better for your child to be mad at you for going through the texts and apps on their cell phone every so often, instead of us having to come to your door and tell you that your child’s been the victim of an online predator.”

For parents who lack the tools to initiate such conversations with their kids, Field recommends the upcoming Parent Project classes that will be hosted this fall by the Los Gatos-Monte Sereno Police Department.

This nationally recognized program offers courses that help parents in dealing with difficult or out-of-control teens and adolescents. Included in the 12-week curriculum–which will be facilitated by county assistant district attorney Mark Buller–are specific strategies for preventing destructive behaviors, such as unsafe Internet access.

“One of the big benefits of the program is that it helps parents understand the new ways in which their kids are operating. They find out about social media, and how kids can become victims at a very young age. Some sites are reaching out to kids as young as 4 and 5,” Field says. “Safety starts at home.”

1–Draft a family media contract spelling out hours of cell phone usage (i.e., 4-7 p.m.) and establishing consequences for misuse; have all parties sign.2–Outside of agreed upon hours, place all cell phones (including parents’) in a receptacle not accessible by children.3–Ensure that you have your child’s current cell phone password at all times.4–Consult with your cell phone provider to learn about and install parental controls (blocking access to adult content, limiting number and origin of text messages, etc.).5–Periodically (and irregularly) inventory all applications and digital content on your child’s phone.6–Restrict Internet access to use in communal areas of the household.7–Change WiFi password daily, restrict access to specific hours.8–Visit your child’s social media pages; be aware of any inappropriate or threatening posts.9–Should cell phone or Internet misuse occur, establish clear-cut “path” needed for child to regain parental trust and use of phone or other device.10–Stay involved, and keep talking to your child. If you lack the ability to do so, don’t hesitate to seek assistance from schools, counselors, law enforcement and/or other professionals.